Merkel cell carcinoma of unknown primary with lymph node and mesenteric metastasis involving the pancreas and duodenum

Merkel cell carcinoma (MCC) of skin is a rare, aggressive cutaneous malignancy of neuroendocrine origin. MCC predominantly affects elderly Caucasians and has high predilection for sun exposed areas. Histologic exam and immunohistochemical profile is required to establish the diagnosis. It has high propensity for local recurrence and metastasis, and carries poor prognosis. However, metastasis to mesentery involving the duodenum is very uncommon and rarely reported in literature. We hereby describe a patient with lymph node and mesenteric metastasis invading duodenum and pancreas with unknown primary origin of MCC.